1 /*
2 * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.inline.hpp"
27 #include "classfile/dictionary.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/symbolTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/icBuffer.hpp"
33 #include "code/nmethod.hpp"
34 #include "code/pcDesc.hpp"
35 #include "code/scopeDesc.hpp"
36 #include "compiler/compilationPolicy.hpp"
37 #include "gc/shared/collectedHeap.hpp"
38 #include "gc/shared/gcLocker.hpp"
39 #include "gc/shared/oopStorage.hpp"
40 #include "gc/shared/strongRootsScope.hpp"
41 #include "gc/shared/workgroup.hpp"
42 #include "interpreter/interpreter.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "logging/log.hpp"
45 #include "logging/logStream.hpp"
46 #include "memory/resourceArea.hpp"
47 #include "memory/universe.hpp"
48 #include "oops/oop.inline.hpp"
49 #include "oops/symbol.hpp"
50 #include "runtime/atomic.hpp"
51 #include "runtime/deoptimization.hpp"
52 #include "runtime/frame.inline.hpp"
53 #include "runtime/handles.inline.hpp"
54 #include "runtime/interfaceSupport.inline.hpp"
55 #include "runtime/mutexLocker.hpp"
56 #include "runtime/orderAccess.hpp"
57 #include "runtime/osThread.hpp"
58 #include "runtime/safepoint.hpp"
59 #include "runtime/safepointMechanism.inline.hpp"
60 #include "runtime/signature.hpp"
61 #include "runtime/stubCodeGenerator.hpp"
62 #include "runtime/stubRoutines.hpp"
63 #include "runtime/sweeper.hpp"
64 #include "runtime/synchronizer.hpp"
65 #include "runtime/thread.inline.hpp"
66 #include "runtime/threadSMR.hpp"
67 #include "runtime/timerTrace.hpp"
68 #include "services/runtimeService.hpp"
69 #include "utilities/events.hpp"
70 #include "utilities/macros.hpp"
71
72 static void post_safepoint_begin_event(EventSafepointBegin& event,
73 uint64_t safepoint_id,
74 int thread_count,
75 int critical_thread_count) {
76 if (event.should_commit()) {
77 event.set_safepointId(safepoint_id);
78 event.set_totalThreadCount(thread_count);
79 event.set_jniCriticalThreadCount(critical_thread_count);
80 event.commit();
81 }
82 }
83
84 static void post_safepoint_cleanup_event(EventSafepointCleanup& event, uint64_t safepoint_id) {
85 if (event.should_commit()) {
86 event.set_safepointId(safepoint_id);
87 event.commit();
88 }
89 }
90
91 static void post_safepoint_synchronize_event(EventSafepointStateSynchronization& event,
92 uint64_t safepoint_id,
93 int initial_number_of_threads,
94 int threads_waiting_to_block,
95 uint64_t iterations) {
96 if (event.should_commit()) {
97 event.set_safepointId(safepoint_id);
98 event.set_initialThreadCount(initial_number_of_threads);
99 event.set_runningThreadCount(threads_waiting_to_block);
100 event.set_iterations(iterations);
101 event.commit();
102 }
103 }
104
105 static void post_safepoint_cleanup_task_event(EventSafepointCleanupTask& event,
106 uint64_t safepoint_id,
107 const char* name) {
108 if (event.should_commit()) {
109 event.set_safepointId(safepoint_id);
110 event.set_name(name);
111 event.commit();
112 }
113 }
114
115 static void post_safepoint_end_event(EventSafepointEnd& event, uint64_t safepoint_id) {
116 if (event.should_commit()) {
117 event.set_safepointId(safepoint_id);
118 event.commit();
119 }
120 }
121
122 // SafepointCheck
123 SafepointStateTracker::SafepointStateTracker(uint64_t safepoint_id, bool at_safepoint)
124 : _safepoint_id(safepoint_id), _at_safepoint(at_safepoint) {}
125
126 bool SafepointStateTracker::safepoint_state_changed() {
127 return _safepoint_id != SafepointSynchronize::safepoint_id() ||
128 _at_safepoint != SafepointSynchronize::is_at_safepoint();
129 }
130
131 // --------------------------------------------------------------------------------------------------
132 // Implementation of Safepoint begin/end
133
134 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
135 int SafepointSynchronize::_waiting_to_block = 0;
136 volatile uint64_t SafepointSynchronize::_safepoint_counter = 0;
137 uint64_t SafepointSynchronize::_safepoint_id = 0;
138 const uint64_t SafepointSynchronize::InactiveSafepointCounter = 0;
139 int SafepointSynchronize::_current_jni_active_count = 0;
140
141 WaitBarrier* SafepointSynchronize::_wait_barrier;
142
143 static bool timeout_error_printed = false;
144
145 // Statistic related
146 static jlong _safepoint_begin_time = 0;
147 static volatile int _nof_threads_hit_polling_page = 0;
148
149 void SafepointSynchronize::init(Thread* vmthread) {
150 // WaitBarrier should never be destroyed since we will have
151 // threads waiting on it while exiting.
152 _wait_barrier = new WaitBarrier(vmthread);
153 SafepointTracing::init();
154 }
155
156 void SafepointSynchronize::increment_jni_active_count() {
157 assert(Thread::current()->is_VM_thread(), "Only VM thread may increment");
158 ++_current_jni_active_count;
159 }
160
161 void SafepointSynchronize::decrement_waiting_to_block() {
162 assert(_waiting_to_block > 0, "sanity check");
163 assert(Thread::current()->is_VM_thread(), "Only VM thread may decrement");
164 --_waiting_to_block;
165 }
166
167 bool SafepointSynchronize::thread_not_running(ThreadSafepointState *cur_state) {
168 if (!cur_state->is_running()) {
169 return true;
170 }
171 cur_state->examine_state_of_thread(SafepointSynchronize::safepoint_counter());
172 if (!cur_state->is_running()) {
173 return true;
174 }
175 LogTarget(Trace, safepoint) lt;
176 if (lt.is_enabled()) {
177 ResourceMark rm;
178 LogStream ls(lt);
179 cur_state->print_on(&ls);
180 }
181 return false;
182 }
183
184 #ifdef ASSERT
185 static void assert_list_is_valid(const ThreadSafepointState* tss_head, int still_running) {
186 int a = 0;
187 const ThreadSafepointState *tmp_tss = tss_head;
188 while (tmp_tss != NULL) {
189 ++a;
190 assert(tmp_tss->is_running(), "Illegal initial state");
191 tmp_tss = tmp_tss->get_next();
192 }
193 assert(a == still_running, "Must be the same");
194 }
195 #endif // ASSERT
196
197 static void back_off(int64_t start_time) {
198 // We start with fine-grained nanosleeping until a millisecond has
199 // passed, at which point we resort to plain naked_short_sleep.
200 if (os::javaTimeNanos() - start_time < NANOSECS_PER_MILLISEC) {
201 os::naked_short_nanosleep(10 * (NANOUNITS / MICROUNITS));
202 } else {
203 os::naked_short_sleep(1);
204 }
205 }
206
207 int SafepointSynchronize::synchronize_threads(jlong safepoint_limit_time, int nof_threads, int* initial_running)
208 {
209 JavaThreadIteratorWithHandle jtiwh;
210
211 #ifdef ASSERT
212 for (; JavaThread *cur = jtiwh.next(); ) {
213 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
214 }
215 jtiwh.rewind();
216 #endif // ASSERT
217
218 // Iterate through all threads until it has been determined how to stop them all at a safepoint.
219 int still_running = nof_threads;
220 ThreadSafepointState *tss_head = NULL;
221 ThreadSafepointState **p_prev = &tss_head;
222 for (; JavaThread *cur = jtiwh.next(); ) {
223 ThreadSafepointState *cur_tss = cur->safepoint_state();
224 assert(cur_tss->get_next() == NULL, "Must be NULL");
225 if (thread_not_running(cur_tss)) {
226 --still_running;
227 } else {
228 *p_prev = cur_tss;
229 p_prev = cur_tss->next_ptr();
230 }
231 }
232 *p_prev = NULL;
233
234 DEBUG_ONLY(assert_list_is_valid(tss_head, still_running);)
235
236 *initial_running = still_running;
237
238 // If there is no thread still running, we are already done.
239 if (still_running <= 0) {
240 assert(tss_head == NULL, "Must be empty");
241 return 1;
242 }
243
244 int iterations = 1; // The first iteration is above.
245 int64_t start_time = os::javaTimeNanos();
246
247 do {
248 // Check if this has taken too long:
249 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
250 print_safepoint_timeout();
251 }
252
253 p_prev = &tss_head;
254 ThreadSafepointState *cur_tss = tss_head;
255 while (cur_tss != NULL) {
256 assert(cur_tss->is_running(), "Illegal initial state");
257 if (thread_not_running(cur_tss)) {
258 --still_running;
259 *p_prev = NULL;
260 ThreadSafepointState *tmp = cur_tss;
261 cur_tss = cur_tss->get_next();
262 tmp->set_next(NULL);
263 } else {
264 *p_prev = cur_tss;
265 p_prev = cur_tss->next_ptr();
266 cur_tss = cur_tss->get_next();
267 }
268 }
269
270 DEBUG_ONLY(assert_list_is_valid(tss_head, still_running);)
271
272 if (still_running > 0) {
273 back_off(start_time);
274 }
275
276 iterations++;
277 } while (still_running > 0);
278
279 assert(tss_head == NULL, "Must be empty");
280
281 return iterations;
282 }
283
284 void SafepointSynchronize::arm_safepoint() {
285 // Begin the process of bringing the system to a safepoint.
286 // Java threads can be in several different states and are
287 // stopped by different mechanisms:
288 //
289 // 1. Running interpreted
290 // When executing branching/returning byte codes interpreter
291 // checks if the poll is armed, if so blocks in SS::block().
292 // 2. Running in native code
293 // When returning from the native code, a Java thread must check
294 // the safepoint _state to see if we must block. If the
295 // VM thread sees a Java thread in native, it does
296 // not wait for this thread to block. The order of the memory
297 // writes and reads of both the safepoint state and the Java
298 // threads state is critical. In order to guarantee that the
299 // memory writes are serialized with respect to each other,
300 // the VM thread issues a memory barrier instruction.
301 // 3. Running compiled Code
302 // Compiled code reads the local polling page that
303 // is set to fault if we are trying to get to a safepoint.
304 // 4. Blocked
305 // A thread which is blocked will not be allowed to return from the
306 // block condition until the safepoint operation is complete.
307 // 5. In VM or Transitioning between states
308 // If a Java thread is currently running in the VM or transitioning
309 // between states, the safepointing code will poll the thread state
310 // until the thread blocks itself when it attempts transitions to a
311 // new state or locking a safepoint checked monitor.
312
313 // We must never miss a thread with correct safepoint id, so we must make sure we arm
314 // the wait barrier for the next safepoint id/counter.
315 // Arming must be done after resetting _current_jni_active_count, _waiting_to_block.
316 _wait_barrier->arm(static_cast<int>(_safepoint_counter + 1));
317
318 assert((_safepoint_counter & 0x1) == 0, "must be even");
319 // The store to _safepoint_counter must happen after any stores in arming.
320 Atomic::release_store(&_safepoint_counter, _safepoint_counter + 1);
321
322 // We are synchronizing
323 OrderAccess::storestore(); // Ordered with _safepoint_counter
324 _state = _synchronizing;
325
326 // Arming the per thread poll while having _state != _not_synchronized means safepointing
327 log_trace(safepoint)("Setting thread local yield flag for threads");
328 OrderAccess::storestore(); // storestore, global state -> local state
329 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) {
330 // Make sure the threads start polling, it is time to yield.
331 SafepointMechanism::arm_local_poll(cur);
332 }
333
334 OrderAccess::fence(); // storestore|storeload, global state -> local state
335 }
336
337 // Roll all threads forward to a safepoint and suspend them all
338 void SafepointSynchronize::begin() {
339 assert(Thread::current()->is_VM_thread(), "Only VM thread may execute a safepoint");
340
341 EventSafepointBegin begin_event;
342 SafepointTracing::begin(VMThread::vm_op_type());
343
344 Universe::heap()->safepoint_synchronize_begin();
345
346 // By getting the Threads_lock, we assure that no threads are about to start or
347 // exit. It is released again in SafepointSynchronize::end().
348 Threads_lock->lock();
349
350 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
351
352 int nof_threads = Threads::number_of_threads();
353
354 _nof_threads_hit_polling_page = 0;
355
356 log_debug(safepoint)("Safepoint synchronization initiated using %s wait barrier. (%d threads)", _wait_barrier->description(), nof_threads);
357
358 // Reset the count of active JNI critical threads
359 _current_jni_active_count = 0;
360
361 // Set number of threads to wait for
362 _waiting_to_block = nof_threads;
363
364 jlong safepoint_limit_time = 0;
365 if (SafepointTimeout) {
366 // Set the limit time, so that it can be compared to see if this has taken
367 // too long to complete.
368 safepoint_limit_time = SafepointTracing::start_of_safepoint() + (jlong)SafepointTimeoutDelay * (NANOUNITS / MILLIUNITS);
369 timeout_error_printed = false;
370 }
371
372 EventSafepointStateSynchronization sync_event;
373 int initial_running = 0;
374
375 // Arms the safepoint, _current_jni_active_count and _waiting_to_block must be set before.
376 arm_safepoint();
377
378 // Will spin until all threads are safe.
379 int iterations = synchronize_threads(safepoint_limit_time, nof_threads, &initial_running);
380 assert(_waiting_to_block == 0, "No thread should be running");
381
382 #ifndef PRODUCT
383 if (safepoint_limit_time != 0) {
384 jlong current_time = os::javaTimeNanos();
385 if (safepoint_limit_time < current_time) {
386 log_warning(safepoint)("# SafepointSynchronize: Finished after "
387 INT64_FORMAT_W(6) " ms",
388 (int64_t)(current_time - SafepointTracing::start_of_safepoint()) / (NANOUNITS / MILLIUNITS));
389 }
390 }
391 #endif
392
393 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
394
395 // Record state
396 _state = _synchronized;
397
398 OrderAccess::fence();
399
400 // Set the new id
401 ++_safepoint_id;
402
403 #ifdef ASSERT
404 // Make sure all the threads were visited.
405 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) {
406 assert(cur->was_visited_for_critical_count(_safepoint_counter), "missed a thread");
407 }
408 #endif // ASSERT
409
410 // Update the count of active JNI critical regions
411 GCLocker::set_jni_lock_count(_current_jni_active_count);
412
413 post_safepoint_synchronize_event(sync_event,
414 _safepoint_id,
415 initial_running,
416 _waiting_to_block, iterations);
417
418 SafepointTracing::synchronized(nof_threads, initial_running, _nof_threads_hit_polling_page);
419
420 // We do the safepoint cleanup first since a GC related safepoint
421 // needs cleanup to be completed before running the GC op.
422 EventSafepointCleanup cleanup_event;
423 do_cleanup_tasks();
424 post_safepoint_cleanup_event(cleanup_event, _safepoint_id);
425
426 post_safepoint_begin_event(begin_event, _safepoint_id, nof_threads, _current_jni_active_count);
427 SafepointTracing::cleanup();
428 }
429
430 void SafepointSynchronize::disarm_safepoint() {
431 uint64_t active_safepoint_counter = _safepoint_counter;
432 {
433 JavaThreadIteratorWithHandle jtiwh;
434 #ifdef ASSERT
435 // A pending_exception cannot be installed during a safepoint. The threads
436 // may install an async exception after they come back from a safepoint into
437 // pending_exception after they unblock. But that should happen later.
438 for (; JavaThread *cur = jtiwh.next(); ) {
439 assert (!(cur->has_pending_exception() &&
440 cur->safepoint_state()->is_at_poll_safepoint()),
441 "safepoint installed a pending exception");
442 }
443 #endif // ASSERT
444
445 OrderAccess::fence(); // keep read and write of _state from floating up
446 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
447
448 // Change state first to _not_synchronized.
449 // No threads should see _synchronized when running.
450 _state = _not_synchronized;
451
452 // Set the next dormant (even) safepoint id.
453 assert((_safepoint_counter & 0x1) == 1, "must be odd");
454 Atomic::release_store(&_safepoint_counter, _safepoint_counter + 1);
455
456 OrderAccess::fence(); // Keep the local state from floating up.
457
458 jtiwh.rewind();
459 for (; JavaThread *current = jtiwh.next(); ) {
460 // Clear the visited flag to ensure that the critical counts are collected properly.
461 DEBUG_ONLY(current->reset_visited_for_critical_count(active_safepoint_counter);)
462 ThreadSafepointState* cur_state = current->safepoint_state();
463 assert(!cur_state->is_running(), "Thread not suspended at safepoint");
464 cur_state->restart(); // TSS _running
465 assert(cur_state->is_running(), "safepoint state has not been reset");
466
467 SafepointMechanism::disarm_if_needed(current, false /* NO release */);
468 }
469 } // ~JavaThreadIteratorWithHandle
470
471 // Release threads lock, so threads can be created/destroyed again.
472 Threads_lock->unlock();
473
474 // Wake threads after local state is correctly set.
475 _wait_barrier->disarm();
476 }
477
478 // Wake up all threads, so they are ready to resume execution after the safepoint
479 // operation has been carried out
480 void SafepointSynchronize::end() {
481 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
482 EventSafepointEnd event;
483 assert(Thread::current()->is_VM_thread(), "Only VM thread can execute a safepoint");
484
485 disarm_safepoint();
486
487 Universe::heap()->safepoint_synchronize_end();
488
489 SafepointTracing::end();
490
491 post_safepoint_end_event(event, safepoint_id());
492 }
493
494 bool SafepointSynchronize::is_cleanup_needed() {
495 // Need a safepoint if there are many monitors to deflate.
496 if (ObjectSynchronizer::is_cleanup_needed()) return true;
497 // Need a safepoint if some inline cache buffers is non-empty
498 if (!InlineCacheBuffer::is_empty()) return true;
499 if (StringTable::needs_rehashing()) return true;
500 if (SymbolTable::needs_rehashing()) return true;
501 return false;
502 }
503
504 bool SafepointSynchronize::is_forced_cleanup_needed() {
505 return ObjectSynchronizer::needs_monitor_scavenge();
506 }
507
508 class ParallelSPCleanupThreadClosure : public ThreadClosure {
509 private:
510 CodeBlobClosure* _nmethod_cl;
511 DeflateMonitorCounters* _counters;
512
513 public:
514 ParallelSPCleanupThreadClosure(DeflateMonitorCounters* counters) :
515 _nmethod_cl(UseCodeAging ? NMethodSweeper::prepare_reset_hotness_counters() : NULL),
516 _counters(counters) {}
517
518 void do_thread(Thread* thread) {
519 ObjectSynchronizer::deflate_thread_local_monitors(thread, _counters);
520 if (_nmethod_cl != NULL && thread->is_Java_thread() &&
521 ! thread->is_Code_cache_sweeper_thread()) {
522 JavaThread* jt = (JavaThread*) thread;
523 jt->nmethods_do(_nmethod_cl);
524 }
525 }
526 };
527
528 class ParallelSPCleanupTask : public AbstractGangTask {
529 private:
530 SubTasksDone _subtasks;
531 ParallelSPCleanupThreadClosure _cleanup_threads_cl;
532 uint _num_workers;
533 DeflateMonitorCounters* _counters;
534 public:
535 ParallelSPCleanupTask(uint num_workers, DeflateMonitorCounters* counters) :
536 AbstractGangTask("Parallel Safepoint Cleanup"),
537 _subtasks(SubTasksDone(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS)),
538 _cleanup_threads_cl(ParallelSPCleanupThreadClosure(counters)),
539 _num_workers(num_workers),
540 _counters(counters) {}
541
542 void work(uint worker_id) {
543 uint64_t safepoint_id = SafepointSynchronize::safepoint_id();
544 // All threads deflate monitors and mark nmethods (if necessary).
545 Threads::possibly_parallel_threads_do(true, &_cleanup_threads_cl);
546
547 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_DEFLATE_MONITORS)) {
548 const char* name = "deflating global idle monitors";
549 EventSafepointCleanupTask event;
550 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
551 ObjectSynchronizer::deflate_idle_monitors(_counters);
552
553 post_safepoint_cleanup_task_event(event, safepoint_id, name);
554 }
555
556 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES)) {
557 const char* name = "updating inline caches";
558 EventSafepointCleanupTask event;
559 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
560 InlineCacheBuffer::update_inline_caches();
561
562 post_safepoint_cleanup_task_event(event, safepoint_id, name);
563 }
564
565 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_COMPILATION_POLICY)) {
566 const char* name = "compilation policy safepoint handler";
567 EventSafepointCleanupTask event;
568 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
569 CompilationPolicy::policy()->do_safepoint_work();
570
571 post_safepoint_cleanup_task_event(event, safepoint_id, name);
572 }
573
574 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH)) {
575 if (SymbolTable::needs_rehashing()) {
576 const char* name = "rehashing symbol table";
577 EventSafepointCleanupTask event;
578 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
579 SymbolTable::rehash_table();
580
581 post_safepoint_cleanup_task_event(event, safepoint_id, name);
582 }
583 }
584
585 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_STRING_TABLE_REHASH)) {
586 if (StringTable::needs_rehashing()) {
587 const char* name = "rehashing string table";
588 EventSafepointCleanupTask event;
589 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
590 StringTable::rehash_table();
591
592 post_safepoint_cleanup_task_event(event, safepoint_id, name);
593 }
594 }
595
596 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE)) {
597 if (Dictionary::does_any_dictionary_needs_resizing()) {
598 const char* name = "resizing system dictionaries";
599 EventSafepointCleanupTask event;
600 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
601 ClassLoaderDataGraph::resize_dictionaries();
602
603 post_safepoint_cleanup_task_event(event, safepoint_id, name);
604 }
605 }
606
607 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_REQUEST_OOPSTORAGE_CLEANUP)) {
608 // Don't bother reporting event or time for this very short operation.
609 // To have any utility we'd also want to report whether needed.
610 OopStorage::trigger_cleanup_if_needed();
611 }
612
613 _subtasks.all_tasks_completed(_num_workers);
614 }
615 };
616
617 // Various cleaning tasks that should be done periodically at safepoints.
618 void SafepointSynchronize::do_cleanup_tasks() {
619
620 TraceTime timer("safepoint cleanup tasks", TRACETIME_LOG(Info, safepoint, cleanup));
621
622 // Prepare for monitor deflation.
623 DeflateMonitorCounters deflate_counters;
624 ObjectSynchronizer::prepare_deflate_idle_monitors(&deflate_counters);
625
626 CollectedHeap* heap = Universe::heap();
627 assert(heap != NULL, "heap not initialized yet?");
628 WorkGang* cleanup_workers = heap->get_safepoint_workers();
629 if (cleanup_workers != NULL) {
630 // Parallel cleanup using GC provided thread pool.
631 uint num_cleanup_workers = cleanup_workers->active_workers();
632 ParallelSPCleanupTask cleanup(num_cleanup_workers, &deflate_counters);
633 StrongRootsScope srs(num_cleanup_workers);
634 cleanup_workers->run_task(&cleanup);
635 } else {
636 // Serial cleanup using VMThread.
637 ParallelSPCleanupTask cleanup(1, &deflate_counters);
638 StrongRootsScope srs(1);
639 cleanup.work(0);
640 }
641
642 // Needs to be done single threaded by the VMThread. This walks
643 // the thread stacks looking for references to metadata before
644 // deciding to remove it from the metaspaces.
645 if (ClassLoaderDataGraph::should_clean_metaspaces_and_reset()) {
646 const char* name = "cleanup live ClassLoaderData metaspaces";
647 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
648 ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces();
649 }
650
651 // Finish monitor deflation.
652 ObjectSynchronizer::finish_deflate_idle_monitors(&deflate_counters);
653
654 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
655 }
656
657 // Methods for determining if a JavaThread is safepoint safe.
658
659 // False means unsafe with undetermined state.
660 // True means a determined state, but it may be an unsafe state.
661 // If called from a non-safepoint context safepoint_count MUST be InactiveSafepointCounter.
662 bool SafepointSynchronize::try_stable_load_state(JavaThreadState *state, JavaThread *thread, uint64_t safepoint_count) {
663 assert((safepoint_count != InactiveSafepointCounter &&
664 Thread::current() == (Thread*)VMThread::vm_thread() &&
665 SafepointSynchronize::_state != _not_synchronized)
666 || safepoint_count == InactiveSafepointCounter, "Invalid check");
667
668 // To handle the thread_blocked state on the backedge of the WaitBarrier from
669 // previous safepoint and reading the reset value (0/InactiveSafepointCounter) we
670 // re-read state after we read thread safepoint id. The JavaThread changes its
671 // thread state from thread_blocked before resetting safepoint id to 0.
672 // This guarantees the second read will be from an updated thread state. It can
673 // either be different state making this an unsafe state or it can see blocked
674 // again. When we see blocked twice with a 0 safepoint id, either:
675 // - It is normally blocked, e.g. on Mutex, TBIVM.
676 // - It was in SS:block(), looped around to SS:block() and is blocked on the WaitBarrier.
677 // - It was in SS:block() but now on a Mutex.
678 // All of these cases are safe.
679
680 *state = thread->thread_state();
681 OrderAccess::loadload();
682 uint64_t sid = thread->safepoint_state()->get_safepoint_id(); // Load acquire
683 if (sid != InactiveSafepointCounter && sid != safepoint_count) {
684 // In an old safepoint, state not relevant.
685 return false;
686 }
687 return *state == thread->thread_state();
688 }
689
690 static bool safepoint_safe_with(JavaThread *thread, JavaThreadState state) {
691 switch(state) {
692 case _thread_in_native:
693 // native threads are safe if they have no java stack or have walkable stack
694 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
695
696 case _thread_blocked:
697 // On wait_barrier or blocked.
698 // Blocked threads should already have walkable stack.
699 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
700 return true;
701
702 default:
703 return false;
704 }
705 }
706
707 bool SafepointSynchronize::handshake_safe(JavaThread *thread) {
708 assert(Thread::current()->is_VM_thread(), "Must be VMThread");
709 if (thread->is_ext_suspended() || thread->is_terminated()) {
710 return true;
711 }
712 JavaThreadState stable_state;
713 if (try_stable_load_state(&stable_state, thread, InactiveSafepointCounter)) {
714 return safepoint_safe_with(thread, stable_state);
715 }
716 return false;
717 }
718
719 // See if the thread is running inside a lazy critical native and
720 // update the thread critical count if so. Also set a suspend flag to
721 // cause the native wrapper to return into the JVM to do the unlock
722 // once the native finishes.
723 static void check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) {
724 if (state == _thread_in_native &&
725 thread->has_last_Java_frame() &&
726 thread->frame_anchor()->walkable()) {
727 // This thread might be in a critical native nmethod so look at
728 // the top of the stack and increment the critical count if it
729 // is.
730 frame wrapper_frame = thread->last_frame();
731 CodeBlob* stub_cb = wrapper_frame.cb();
732 if (stub_cb != NULL &&
733 stub_cb->is_nmethod() &&
734 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) {
735 // A thread could potentially be in a critical native across
736 // more than one safepoint, so only update the critical state on
737 // the first one. When it returns it will perform the unlock.
738 if (!thread->do_critical_native_unlock()) {
739 #ifdef ASSERT
740 if (!thread->in_critical()) {
741 GCLocker::increment_debug_jni_lock_count();
742 }
743 #endif
744 thread->enter_critical();
745 // Make sure the native wrapper calls back on return to
746 // perform the needed critical unlock.
747 thread->set_critical_native_unlock();
748 }
749 }
750 }
751 }
752
753 // -------------------------------------------------------------------------------------------------------
754 // Implementation of Safepoint blocking point
755
756 void SafepointSynchronize::block(JavaThread *thread) {
757 assert(thread != NULL, "thread must be set");
758 assert(thread->is_Java_thread(), "not a Java thread");
759
760 // Threads shouldn't block if they are in the middle of printing, but...
761 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
762
763 // Only bail from the block() call if the thread is gone from the
764 // thread list; starting to exit should still block.
765 if (thread->is_terminated()) {
766 // block current thread if we come here from native code when VM is gone
767 thread->block_if_vm_exited();
768
769 // otherwise do nothing
770 return;
771 }
772
773 JavaThreadState state = thread->thread_state();
774 thread->frame_anchor()->make_walkable(thread);
775
776 uint64_t safepoint_id = SafepointSynchronize::safepoint_counter();
777 // Check that we have a valid thread_state at this point
778 switch(state) {
779 case _thread_in_vm_trans:
780 case _thread_in_Java: // From compiled code
781 case _thread_in_native_trans:
782 case _thread_blocked_trans:
783 case _thread_new_trans:
784
785 // We have no idea where the VMThread is, it might even be at next safepoint.
786 // So we can miss this poll, but stop at next.
787
788 // Load dependent store, it must not pass loading of safepoint_id.
789 thread->safepoint_state()->set_safepoint_id(safepoint_id); // Release store
790
791 // This part we can skip if we notice we miss or are in a future safepoint.
792 OrderAccess::storestore();
793 // Load in wait barrier should not float up
794 thread->set_thread_state_fence(_thread_blocked);
795
796 _wait_barrier->wait(static_cast<int>(safepoint_id));
797 assert(_state != _synchronized, "Can't be");
798
799 // If barrier is disarmed stop store from floating above loads in barrier.
800 OrderAccess::loadstore();
801 thread->set_thread_state(state);
802
803 // Then we reset the safepoint id to inactive.
804 thread->safepoint_state()->reset_safepoint_id(); // Release store
805
806 OrderAccess::fence();
807
808 break;
809
810 default:
811 fatal("Illegal threadstate encountered: %d", state);
812 }
813 guarantee(thread->safepoint_state()->get_safepoint_id() == InactiveSafepointCounter,
814 "The safepoint id should be set only in block path");
815
816 // Check for pending. async. exceptions or suspends - except if the
817 // thread was blocked inside the VM. has_special_runtime_exit_condition()
818 // is called last since it grabs a lock and we only want to do that when
819 // we must.
820 //
821 // Note: we never deliver an async exception at a polling point as the
822 // compiler may not have an exception handler for it. The polling
823 // code will notice the async and deoptimize and the exception will
824 // be delivered. (Polling at a return point is ok though). Sure is
825 // a lot of bother for a deprecated feature...
826 //
827 // We don't deliver an async exception if the thread state is
828 // _thread_in_native_trans so JNI functions won't be called with
829 // a surprising pending exception. If the thread state is going back to java,
830 // async exception is checked in check_special_condition_for_native_trans().
831
832 if (state != _thread_blocked_trans &&
833 state != _thread_in_vm_trans &&
834 thread->has_special_runtime_exit_condition()) {
835 thread->handle_special_runtime_exit_condition(
836 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
837 }
838
839 // cross_modify_fence is done by SafepointMechanism::block_if_requested_slow
840 // which is the only caller here.
841 }
842
843 // ------------------------------------------------------------------------------------------------------
844 // Exception handlers
845
846
847 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
848 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
849 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
850
851 if (log_is_enabled(Info, safepoint, stats)) {
852 Atomic::inc(&_nof_threads_hit_polling_page);
853 }
854
855 ThreadSafepointState* state = thread->safepoint_state();
856
857 state->handle_polling_page_exception();
858 }
859
860
861 void SafepointSynchronize::print_safepoint_timeout() {
862 if (!timeout_error_printed) {
863 timeout_error_printed = true;
864 // Print out the thread info which didn't reach the safepoint for debugging
865 // purposes (useful when there are lots of threads in the debugger).
866 LogTarget(Warning, safepoint) lt;
867 if (lt.is_enabled()) {
868 ResourceMark rm;
869 LogStream ls(lt);
870
871 ls.cr();
872 ls.print_cr("# SafepointSynchronize::begin: Timeout detected:");
873 ls.print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
874 ls.print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
875 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) {
876 if (cur_thread->safepoint_state()->is_running()) {
877 ls.print("# ");
878 cur_thread->print_on(&ls);
879 ls.cr();
880 }
881 }
882 ls.print_cr("# SafepointSynchronize::begin: (End of list)");
883 }
884 }
885
886 // To debug the long safepoint, specify both AbortVMOnSafepointTimeout &
887 // ShowMessageBoxOnError.
888 if (AbortVMOnSafepointTimeout) {
889 // Send the blocking thread a signal to terminate and write an error file.
890 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) {
891 if (cur_thread->safepoint_state()->is_running()) {
892 if (!os::signal_thread(cur_thread, SIGILL, "blocking a safepoint")) {
893 break; // Could not send signal. Report fatal error.
894 }
895 // Give cur_thread a chance to report the error and terminate the VM.
896 os::naked_sleep(3000);
897 }
898 }
899 fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
900 SafepointTimeoutDelay, VMThread::vm_operation()->name());
901 }
902 }
903
904 // -------------------------------------------------------------------------------------------------------
905 // Implementation of ThreadSafepointState
906
907 ThreadSafepointState::ThreadSafepointState(JavaThread *thread)
908 : _at_poll_safepoint(false), _thread(thread), _safepoint_safe(false),
909 _safepoint_id(SafepointSynchronize::InactiveSafepointCounter), _next(NULL) {
910 }
911
912 void ThreadSafepointState::create(JavaThread *thread) {
913 ThreadSafepointState *state = new ThreadSafepointState(thread);
914 thread->set_safepoint_state(state);
915 }
916
917 void ThreadSafepointState::destroy(JavaThread *thread) {
918 if (thread->safepoint_state()) {
919 delete(thread->safepoint_state());
920 thread->set_safepoint_state(NULL);
921 }
922 }
923
924 uint64_t ThreadSafepointState::get_safepoint_id() const {
925 return Atomic::load_acquire(&_safepoint_id);
926 }
927
928 void ThreadSafepointState::reset_safepoint_id() {
929 Atomic::release_store(&_safepoint_id, SafepointSynchronize::InactiveSafepointCounter);
930 }
931
932 void ThreadSafepointState::set_safepoint_id(uint64_t safepoint_id) {
933 Atomic::release_store(&_safepoint_id, safepoint_id);
934 }
935
936 void ThreadSafepointState::examine_state_of_thread(uint64_t safepoint_count) {
937 assert(is_running(), "better be running or just have hit safepoint poll");
938
939 JavaThreadState stable_state;
940 if (!SafepointSynchronize::try_stable_load_state(&stable_state, _thread, safepoint_count)) {
941 // We could not get stable state of the JavaThread.
942 // Consider it running and just return.
943 return;
944 }
945
946 // Check for a thread that is suspended. Note that thread resume tries
947 // to grab the Threads_lock which we own here, so a thread cannot be
948 // resumed during safepoint synchronization.
949
950 // We check to see if this thread is suspended without locking to
951 // avoid deadlocking with a third thread that is waiting for this
952 // thread to be suspended. The third thread can notice the safepoint
953 // that we're trying to start at the beginning of its SR_lock->wait()
954 // call. If that happens, then the third thread will block on the
955 // safepoint while still holding the underlying SR_lock. We won't be
956 // able to get the SR_lock and we'll deadlock.
957 //
958 // We don't need to grab the SR_lock here for two reasons:
959 // 1) The suspend flags are both volatile and are set with an
960 // Atomic::cmpxchg() call so we should see the suspended
961 // state right away.
962 // 2) We're being called from the safepoint polling loop; if
963 // we don't see the suspended state on this iteration, then
964 // we'll come around again.
965 //
966 bool is_suspended = _thread->is_ext_suspended();
967 if (is_suspended) {
968 account_safe_thread();
969 return;
970 }
971
972 if (safepoint_safe_with(_thread, stable_state)) {
973 check_for_lazy_critical_native(_thread, stable_state);
974 account_safe_thread();
975 return;
976 }
977
978 // All other thread states will continue to run until they
979 // transition and self-block in state _blocked
980 // Safepoint polling in compiled code causes the Java threads to do the same.
981 // Note: new threads may require a malloc so they must be allowed to finish
982
983 assert(is_running(), "examine_state_of_thread on non-running thread");
984 return;
985 }
986
987 void ThreadSafepointState::account_safe_thread() {
988 SafepointSynchronize::decrement_waiting_to_block();
989 if (_thread->in_critical()) {
990 // Notice that this thread is in a critical section
991 SafepointSynchronize::increment_jni_active_count();
992 }
993 DEBUG_ONLY(_thread->set_visited_for_critical_count(SafepointSynchronize::safepoint_counter());)
994 assert(!_safepoint_safe, "Must be unsafe before safe");
995 _safepoint_safe = true;
996 }
997
998 void ThreadSafepointState::restart() {
999 assert(_safepoint_safe, "Must be safe before unsafe");
1000 _safepoint_safe = false;
1001 }
1002
1003 void ThreadSafepointState::print_on(outputStream *st) const {
1004 const char *s = _safepoint_safe ? "_at_safepoint" : "_running";
1005
1006 st->print_cr("Thread: " INTPTR_FORMAT
1007 " [0x%2x] State: %s _at_poll_safepoint %d",
1008 p2i(_thread), _thread->osthread()->thread_id(), s, _at_poll_safepoint);
1009
1010 _thread->print_thread_state_on(st);
1011 }
1012
1013 // ---------------------------------------------------------------------------------------------------------------------
1014
1015 // Block the thread at poll or poll return for safepoint/handshake.
1016 void ThreadSafepointState::handle_polling_page_exception() {
1017
1018 // Step 1: Find the nmethod from the return address
1019 address real_return_addr = thread()->saved_exception_pc();
1020
1021 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
1022 assert(cb != NULL && cb->is_compiled(), "return address should be in nmethod");
1023 CompiledMethod* nm = (CompiledMethod*)cb;
1024
1025 // Find frame of caller
1026 frame stub_fr = thread()->last_frame();
1027 CodeBlob* stub_cb = stub_fr.cb();
1028 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
1029 RegisterMap map(thread(), true);
1030 frame caller_fr = stub_fr.sender(&map);
1031
1032 // Should only be poll_return or poll
1033 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
1034
1035 // This is a poll immediately before a return. The exception handling code
1036 // has already had the effect of causing the return to occur, so the execution
1037 // will continue immediately after the call. In addition, the oopmap at the
1038 // return point does not mark the return value as an oop (if it is), so
1039 // it needs a handle here to be updated.
1040 if( nm->is_at_poll_return(real_return_addr) ) {
1041 // See if return type is an oop.
1042 bool return_oop = nm->method()->is_returning_oop();
1043 Handle return_value;
1044 if (return_oop) {
1045 // The oop result has been saved on the stack together with all
1046 // the other registers. In order to preserve it over GCs we need
1047 // to keep it in a handle.
1048 oop result = caller_fr.saved_oop_result(&map);
1049 assert(oopDesc::is_oop_or_null(result), "must be oop");
1050 return_value = Handle(thread(), result);
1051 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
1052 }
1053
1054 // Block the thread
1055 SafepointMechanism::block_if_requested(thread());
1056
1057 // restore oop result, if any
1058 if (return_oop) {
1059 caller_fr.set_saved_oop_result(&map, return_value());
1060 }
1061 }
1062
1063 // This is a safepoint poll. Verify the return address and block.
1064 else {
1065 set_at_poll_safepoint(true);
1066
1067 // verify the blob built the "return address" correctly
1068 assert(real_return_addr == caller_fr.pc(), "must match");
1069
1070 // Block the thread
1071 SafepointMechanism::block_if_requested(thread());
1072 set_at_poll_safepoint(false);
1073
1074 // If we have a pending async exception deoptimize the frame
1075 // as otherwise we may never deliver it.
1076 if (thread()->has_async_condition()) {
1077 ThreadInVMfromJavaNoAsyncException __tiv(thread());
1078 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
1079 }
1080
1081 // If an exception has been installed we must check for a pending deoptimization
1082 // Deoptimize frame if exception has been thrown.
1083
1084 if (thread()->has_pending_exception() ) {
1085 RegisterMap map(thread(), true);
1086 frame caller_fr = stub_fr.sender(&map);
1087 if (caller_fr.is_deoptimized_frame()) {
1088 // The exception patch will destroy registers that are still
1089 // live and will be needed during deoptimization. Defer the
1090 // Async exception should have deferred the exception until the
1091 // next safepoint which will be detected when we get into
1092 // the interpreter so if we have an exception now things
1093 // are messed up.
1094
1095 fatal("Exception installed and deoptimization is pending");
1096 }
1097 }
1098 }
1099 }
1100
1101
1102 // -------------------------------------------------------------------------------------------------------
1103 // Implementation of SafepointTracing
1104
1105 jlong SafepointTracing::_last_safepoint_begin_time_ns = 0;
1106 jlong SafepointTracing::_last_safepoint_sync_time_ns = 0;
1107 jlong SafepointTracing::_last_safepoint_cleanup_time_ns = 0;
1108 jlong SafepointTracing::_last_safepoint_end_time_ns = 0;
1109 jlong SafepointTracing::_last_app_time_ns = 0;
1110 int SafepointTracing::_nof_threads = 0;
1111 int SafepointTracing::_nof_running = 0;
1112 int SafepointTracing::_page_trap = 0;
1113 VM_Operation::VMOp_Type SafepointTracing::_current_type;
1114 jlong SafepointTracing::_max_sync_time = 0;
1115 jlong SafepointTracing::_max_vmop_time = 0;
1116 uint64_t SafepointTracing::_op_count[VM_Operation::VMOp_Terminating] = {0};
1117
1118 void SafepointTracing::init() {
1119 // Application start
1120 _last_safepoint_end_time_ns = os::javaTimeNanos();
1121 }
1122
1123 // Helper method to print the header.
1124 static void print_header(outputStream* st) {
1125 // The number of spaces is significant here, and should match the format
1126 // specifiers in print_statistics().
1127
1128 st->print("VM Operation "
1129 "[ threads: total initial_running ]"
1130 "[ time: sync cleanup vmop total ]");
1131
1132 st->print_cr(" page_trap_count");
1133 }
1134
1135 // This prints a nice table. To get the statistics to not shift due to the logging uptime
1136 // decorator, use the option as: -Xlog:safepoint+stats:[outputfile]:none
1137 void SafepointTracing::statistics_log() {
1138 LogTarget(Info, safepoint, stats) lt;
1139 assert (lt.is_enabled(), "should only be called when printing statistics is enabled");
1140 LogStream ls(lt);
1141
1142 static int _cur_stat_index = 0;
1143
1144 // Print header every 30 entries
1145 if ((_cur_stat_index % 30) == 0) {
1146 print_header(&ls);
1147 _cur_stat_index = 1; // wrap
1148 } else {
1149 _cur_stat_index++;
1150 }
1151
1152 ls.print("%-28s [ "
1153 INT32_FORMAT_W(8) " " INT32_FORMAT_W(8) " "
1154 "]",
1155 VM_Operation::name(_current_type),
1156 _nof_threads,
1157 _nof_running);
1158 ls.print("[ "
1159 INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " "
1160 INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " ]",
1161 (int64_t)(_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns),
1162 (int64_t)(_last_safepoint_cleanup_time_ns - _last_safepoint_sync_time_ns),
1163 (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns),
1164 (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_begin_time_ns));
1165
1166 ls.print_cr(INT32_FORMAT_W(16), _page_trap);
1167 }
1168
1169 // This method will be called when VM exits. This tries to summarize the sampling.
1170 // Current thread may already be deleted, so don't use ResourceMark.
1171 void SafepointTracing::statistics_exit_log() {
1172 if (!log_is_enabled(Info, safepoint, stats)) {
1173 return;
1174 }
1175 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
1176 if (_op_count[index] != 0) {
1177 log_info(safepoint, stats)("%-28s" UINT64_FORMAT_W(10), VM_Operation::name(index),
1178 _op_count[index]);
1179 }
1180 }
1181
1182 log_info(safepoint, stats)("VM operations coalesced during safepoint " INT64_FORMAT,
1183 VMThread::get_coalesced_count());
1184 log_info(safepoint, stats)("Maximum sync time " INT64_FORMAT" ns",
1185 (int64_t)(_max_sync_time));
1186 log_info(safepoint, stats)("Maximum vm operation time (except for Exit VM operation) "
1187 INT64_FORMAT " ns",
1188 (int64_t)(_max_vmop_time));
1189 }
1190
1191 void SafepointTracing::begin(VM_Operation::VMOp_Type type) {
1192 _op_count[type]++;
1193 _current_type = type;
1194
1195 // update the time stamp to begin recording safepoint time
1196 _last_safepoint_begin_time_ns = os::javaTimeNanos();
1197 _last_safepoint_sync_time_ns = 0;
1198 _last_safepoint_cleanup_time_ns = 0;
1199
1200 _last_app_time_ns = _last_safepoint_begin_time_ns - _last_safepoint_end_time_ns;
1201 _last_safepoint_end_time_ns = 0;
1202
1203 RuntimeService::record_safepoint_begin(_last_app_time_ns);
1204 }
1205
1206 void SafepointTracing::synchronized(int nof_threads, int nof_running, int traps) {
1207 _last_safepoint_sync_time_ns = os::javaTimeNanos();
1208 _nof_threads = nof_threads;
1209 _nof_running = nof_running;
1210 _page_trap = traps;
1211 RuntimeService::record_safepoint_synchronized(_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns);
1212 }
1213
1214 void SafepointTracing::cleanup() {
1215 _last_safepoint_cleanup_time_ns = os::javaTimeNanos();
1216 }
1217
1218 void SafepointTracing::end() {
1219 _last_safepoint_end_time_ns = os::javaTimeNanos();
1220
1221 if (_max_sync_time < (_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns)) {
1222 _max_sync_time = _last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns;
1223 }
1224 if (_max_vmop_time < (_last_safepoint_end_time_ns - _last_safepoint_sync_time_ns)) {
1225 _max_vmop_time = _last_safepoint_end_time_ns - _last_safepoint_sync_time_ns;
1226 }
1227 if (log_is_enabled(Info, safepoint, stats)) {
1228 statistics_log();
1229 }
1230
1231 log_info(safepoint)(
1232 "Safepoint \"%s\", "
1233 "Time since last: " JLONG_FORMAT " ns, "
1234 "Reaching safepoint: " JLONG_FORMAT " ns, "
1235 "At safepoint: " JLONG_FORMAT " ns, "
1236 "Total: " JLONG_FORMAT " ns",
1237 VM_Operation::name(_current_type),
1238 _last_app_time_ns,
1239 _last_safepoint_cleanup_time_ns - _last_safepoint_begin_time_ns,
1240 _last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns,
1241 _last_safepoint_end_time_ns - _last_safepoint_begin_time_ns
1242 );
1243
1244 RuntimeService::record_safepoint_end(_last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns);
1245 }